1. Field of the Invention
The present invention relates to a novel peptide, a process for the production thereof, and a pharmaceutical composition containing the novel peptide as a diuretic or hypotensor.
2. Description of the Related Art
A normal regulation of the blood pressure in a human body is important for the maintenance of personal health, and various physical and humoral factors contribute to this regulation of the blood pressure. The physical factors include, for example, output, and the elasticity of the walls of blood vessels, etc. The humoral factors include, for example, the renin-angiotensin-aldosterone system, catecholamines, prostaglandins, kinin-kallikrein system, and natriuretic hormones including ouabain-like substances. Herein the term "natriuretic" will denote selective excretion of sodium cation relating to potassium cation.
Granules morphologically similar to granules present in peptide hormone-producing cells are found in human atrium (J. D. Jamieson and G. E. Palade, J. Cell Biol., 23, 151, 1964). A homogenate of rat atrium and granules contained therein are known to show natriuretic action in rats (A. J. DeBold et. al., Life Science, 28, 89, 1981; R. Keeler, Can. J. Physiol. Pharmacol., 60, 1078, 1982). Recently Mark G. Currie et. al. suggested peptide-like substances with a molecular weight of 20,000 to 30,000 or not more than 10,000, present in atrium of humans, rabbits, swine, and rats, and having natriuretic action (Science, 221, 71-73, 1983).
Moreover, a peptide consisting of 28 amino acids derived from rat atrium cordis was identified (Biochem. Biophys. Res. Commun., Vol. 117, No. 3, p859-865, 1983). The present inventors found a new peptide consisting of 28 amino acids from human atrium cordis; referred to as ".alpha.-human atrial natriuretic polypeptide" and abbreviated as ".alpha.-hANP" (Biochem. Biophys. Res. Commun.) Vol. 118, No. 1, p131-139, 1984).